1. Field of the Invention
The present invention relates to a manufacturing method of a solid-state imaging apparatus (solid-state imaging device) such as a CCD sensor and a CMOS sensor.
2. Description of the Related Art
A technique for improving the light collecting efficiency of receiving portions, particularly, a technique of more efficiently collecting light with a steep incident angle, is desired in a solid-state imaging apparatus. For example, a solid-state imaging apparatus is proposed in recent years, wherein hollow portions are formed in boundary areas of color filters formed above light receiving portions, and reflection of hollow portion interfaces is used to improve the light collecting efficiency of the light receiving portions (for example, see Japanese Patent Application Laid-Open No. 2009-088415).
A formation method of the hollow portions illustrated in Japanese Patent Application Laid-Open No. 2009-088415 will be described.
FIGS. 6A to 6D are schematic views illustrating an outline of forming hollow portions in boundary areas of color filters in a manufacturing method of a solid-state imaging apparatus described in Japanese Patent Application Laid-Open No. 2009-088415.
In Japanese Patent Application Laid-Open No. 2009-088415, a first color filter is formed in a predetermined area on a planarized layer as illustrated in FIG. 6A. A thin sacrificial layer is formed on the entire surface including the surface of the first color filter.
As illustrated in FIG. 6B, anisotropic dry etching is used to etch-back the sacrificial layer. The sacrificial layer is left only on the side walls of the first color filter, and the sacrificial layer is removed from the rest of the surface.
As illustrated in FIG. 6C, a second color filter is formed on the planarized layer, adjacent to one of the sides of the first color filter, through the sacrificial layer. A third color film is formed on the planarized layer, adjacent to the other side of the first color filter, through the sacrificial layer.
As illustrated in FIG. 6D, the sacrificial layer is removed by etching, and hollow portions are formed between the color filters.
However, in the method described in Japanese Patent Application Laid-Open No. 2009-088415, when the second and third color filters are formed to cover the upper surfaces of the sacrificial layer formed on the side walls of the first color filter in the step illustrated in FIG. 6C, the sacrificial layer may not be removed by the etching process, and the hollow portions may not be formed.
The present invention has been made in view of the problem, and an object of the present invention is to provide a manufacturing method of a solid-state imaging apparatus that allows more stable formation of hollow portions between color filters.